Water-tube boiler.



N0 MODEL.

INVENTOR.

WITNESSES.-

B uzfiffa/w /v Wm UNITED STATES Patented June 9, 1903.

GUNDER HANSEN, OF SAN FRANCISCO, CALIFORNIA.

-WATEFt-TUBE-BOILER.

SPECIFICATION forming part of Letters Patent No. 7 30,765, dated J true9, 1903. Application filed October 28, 1902. Serial No. 129,150. (Nomodel.)

To all whom it may concern:

Be it known that I, GUNDER HANSEN, a citizen of the United States,residing at 154 Hawthorn street, in the city of San Francisco,

county of San Francisco, and State of Calito the changes of temperaturewithin the furnace.

All water-tube boilers wherein the water circulates through a mass oftubes extending between hollow heads are subject to the greatdisadvantage of leakage at the joint of the tube with the head. Thisweak feature in many instances more than offsets the many advantages ofthis type of boiler. These leaks invariablyoccur near the furnace-doors.

This is due to the cold air rushing inwhen the doors are open forstoking, chilling the tubes and causing contraction sufficient to openthe joint between the tube and the head. The corrosive action of thewater escaping through the leak in the influence of intense heat,together with the internal pressure, soon cripples the whole boiler. Theaverage life of aset of tubes in the boiler uponwhich I haveexperimented has heretofore been about seven months. Since theapplication of this invention, the tubes have stood constant work fornearly a year without appreciable deterioration.

The object of this invention is to protect the tube-joints from thermalchanges prod ucing expansion andcontraction.

The invention consists, broadly, of a fireresisting substance outlinedto conform to the contour of the joints of the tubes with the head, intowhich they are set, whereby the joint is protected from the direct heatof the furnace and the chilling-drafts entering the furnace.

In the drawings,Figure 1 is a side'elevation, partly in cross-section,of a marine boiler of the water-tube type, showing the application ofthis invention. Fig. 2 is a front elevation in cross-section of one sideof the furnace above the grate-bars, showing the circulation-tubesforming the side of the furnace and a few tubes in the first tier of theboiler with this invention applied thereto. Fig. 3 is an isometricalperspective of one of the bricks for protectionof the horizontal tubes,showing the recess for the attaching-bolt.

The same general principles enter into the construction of allwater-tube boilers and all are more or less subject to the disadvantagewhich it is the object of this invention to overcome.

As illustrated, the furnace is provided with the usual grate-bars,bridge-wall, and stokedoors, the sides being formed by the drums A,attached to the standing drums A A? by the nipples A front and back,respectively. From these drums the water circulates upward into thehollow heads B and B, between which the tier of tubes B forming the topof the furnace, and the mass of tubes B extend around, and between whichthe products of combustion are cansedto circulate before escapingthrough the smoke-stack. Under the influence of the accumulatingpressure in the steam-drum C and the evaporation of the water a constantcirculation within the boiler is maintained. with their variouscooperative members being the weakest point in the structure, the forcesof destruction culminate at this point, particularly in the locations offluctuating temperature. For instance, in the front of the furnace, inthe path of the cold air entering through the furnace-doors and throughthe dead-rise D, the nipples A and joints of the tubes B with the head Bgive constant trouble. This is due to the fact that the tubes becomeheated and expanded by the furmace-fires and then chilled and contractedby the cold drafts as the damper is changed or the doors opened. Thisconstant expansion and contraction must result in opening the joint,with its obvious consequences. These consequences are entirely obviatedby the operation of this invention, which consists of protecting thenipples A by the member E, (preferably cast-iron,) which conforms to theoutline of the joint and is held in place by The joint of the tubes"IOCI location therein.

the bolt E passing through the side of the furnace. The member E servesthe'double purpose of protecting the joint from the corrosive action ofthe fire and by reason of its mass becoming heated maintains an eventemperature at this point'during the interval that the door may be open.These same results are accomplished by the members F, which beinglocated ina higher temperature are preferably molded of fire-brick insections of suitable form to allow of their convenient application tothe joint. In this instance they are held in pairs between the tubes bythe bolts F. Obviously the exact form will vary with the type of boileror its It has proven unnecessary to protect the joints not subjected tocold drafts, because the expansion and contraction therein arepractically nil.

Having determined that it is the expansion and contraction in the jointsof water-tube boilers that cause them to leak, and having thus describedmy invention, what I claim, and desire to secure by Letters Patent, is-

tecting the joints therein from abnormal I thermal fluctuations,comprising a covering member formed in sections and having portionsconforming to the shape of said joints, and bolts interposed between themeeting faces of said sections, said meeting faces being channeled orrecessed to receive said bolts, as set forth.

In testimony whereof I have hereunto set my hand this 30th day ofSeptember, 1902.

GUNDER HANSEN.

Witnesses:

BALDWIN VALE, G. F. I-IAT'roN.

